1 /*
2 * include/asm-xtensa/dma.h
3 *
4 * This file is subject to the terms and conditions of the GNU General Public
5 * License. See the file "COPYING" in the main directory of this archive
6 * for more details.
7 *
8 * Copyright (C) 2003 - 2005 Tensilica Inc.
9 */
10
11 #ifndef _XTENSA_DMA_H
12 #define _XTENSA_DMA_H
13
14 #include <asm/io.h> /* need byte IO */
15
16 /*
17 * This is only to be defined if we have PC-like DMA.
18 * By default this is not true on an Xtensa processor,
19 * however on boards with a PCI bus, such functionality
20 * might be emulated externally.
21 *
22 * NOTE: there still exists driver code that assumes
23 * this is defined, eg. drivers/sound/soundcard.c (as of 2.4).
24 */
25 #define MAX_DMA_CHANNELS 8
26
27 /*
28 * The maximum virtual address to which DMA transfers
29 * can be performed on this platform.
30 *
31 * NOTE: This is board (platform) specific, not processor-specific!
32 *
33 * NOTE: This assumes DMA transfers can only be performed on
34 * the section of physical memory contiguously mapped in virtual
35 * space for the kernel. For the Xtensa architecture, this
36 * means the maximum possible size of this DMA area is
37 * the size of the statically mapped kernel segment
38 * (XCHAL_KSEG_{CACHED,BYPASS}_SIZE), ie. 128 MB.
39 *
40 * NOTE: When the entire KSEG area is DMA capable, we subtract
41 * one from the max address so that the virt_to_phys() macro
42 * works correctly on the address (otherwise the address
43 * enters another area, and virt_to_phys() may not return
44 * the value desired).
45 */
46
47 #ifndef MAX_DMA_ADDRESS
48 #define MAX_DMA_ADDRESS (PAGE_OFFSET + XCHAL_KIO_SIZE - 1)
49 #endif
50
51 /* Reserve and release a DMA channel */
52 extern int request_dma(unsigned int dmanr, const char * device_id);
53 extern void free_dma(unsigned int dmanr);
54
55 #endif
56
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